/*
 * Copyright 2000-2016 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.openapi.util;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * @author ven
 */
public class Ref<T> {
    private T myValue;

    public Ref() {
    }

    public Ref(@Nullable T value) {
        myValue = value;
    }

    public final boolean isNull() {
        return myValue == null;
    }

    public final T get() {
        return myValue;
    }

    public final void set(@Nullable T value) {
        myValue = value;
    }

    public final boolean setIfNull(@Nullable T value) {
        if (myValue == null) {
            myValue = value;
            return true;
        }
        return false;
    }

    @NotNull
    public static <T> Ref<T> create() {
        return new Ref<T>();
    }

    public static <T> Ref<T> create(@Nullable T value) {
        return new Ref<T>(value);
    }

    @Nullable
    public static <T> T deref(@Nullable Ref<T> ref) {
        return ref == null ? null : ref.get();
    }

    @Override
    public String toString() {
        return String.valueOf(myValue);
    }
}
